Toyota A25A-FKS 2.5 D-4S Engine Specs, Problems, Reliability. Toyota presented the A25A-FKS or 2.5 D-4S engine in 2016 like the very first member of its brand-new engine family “Dynamic Force Engines”. It is a 2.5-liter inline four-cylinder gasoline engine combined the newest Toyota’s internal-combustion innovations which can be discovered separately in previous engines produced in the last years.
The A25A engine has a brand-new open-deck aluminum alloy cylinder block with sleeves cast straight in block product. The longitudinal axis of the crankshaft has a 10 mm offset versus the axes of the cylinders. The crankshaft has 7 traditional counterweights and one with tooth gear. That equipment on the crankshaft drives the stabilizing unit attached to the engine block at the bottom. The engine got the high-strength connecting rods and lightweight aluminum T-shape pistons with an unique resin finish. The upper compression and oil rings have a DLC finish (Diamond Like Carbon). The pistons are cooled with engine oil sprayed by 2 oil jets for each piston. The oil system was likewise upgraded. The main innovation is the second generation variable-pressure oil pump controlled by ECM electronics.
The engine has an aluminum 16-valve cylinder head with 2 chain-driven camshafts in separate housing at the top. The angle in between the consumption and exhaust valve is 41 deg. The consumption port has a laser-cladded valve seat while the exhaust has actually a regular pressed valve seat. The valves are activated by camshafts by means of roller rocker arms. The engine is equipped with hydraulic tappets for continues zero valve clearance. The intake and exhaust camshafts are driven by low-friction single-row timing chain with a pitch of 8.0 mm.
Toyota A25A-FKS 2.5 D-4S Engine Specs, Problems, Reliability
The A25A-FKS includes the Dual Variable Valve Timing system (DVVT). The electrical actuator (VVT-iE) is utilized for the consumption camshaft; the standard hydraulic VVT actuator was attached to the exhaust camshaft. The exhaust camshaft has an additional webcam for the high-pressure fuel pump. The head cover is made from polymer material.
The A25A engine has a combined fuel injection – in the combustion chambers (direct) and in the intake ports (multipoint). That Toyota’s system is named as D-4S. Each high-pressure fuel nozzle for direct injection has six holes and spray fuel at mid and high engine loads. The low-pressure nozzles in ports have 10 holes. The multipoint fuel injection operates at low speeds and at mid-range together with direct injection. The fuel pressure in the system is a series of 2.4-20 MPa.
The engine has a simple fixed-geometry plastic intake manifold and digitally controlled throttle body – ETCS-i. There is no restricted air in the intake manifold, because factor the engine was equipped with a vacuum pump driven by exhaust camshaft to create sufficient vacuum in a brake booster. From the exhaust side, there is a stainless-steel exhaust manifold (header) with integrated catalyst converter and EGR pipe.
The contemporary ecological guidelines forced the big modifications in the engine cooling system of the engines. The 2.5 D-4S engine has an electric motor-driven water pump, electronically managed thermostat, and shut-off valves. The new system adds to faster heat up and ideal cooling on all loads vary.
In the result, the brand-new 2.5-liter power plant is the most highly sophisticated engine ever produced by Toyota. The maximum thermal efficiency attained the line of 40% – among the world’s finest results for a conventional engine. Now, when the A25A-FKS moved the output and fuel economy on the next level, the 2AR became the past.
Toyota A25A-FKS 2.5 D-4S Engine Problems and Reliability
The engine has much more intricate style compared to the 2AR engine series. There are a lot of electronic devices, sensors and small parts as a potential failure. Hope, that Toyota still utilizes good quality parts and precise assembly. We also can see what the laser-clad seats in the head are plain, and the cast-in cylinder sleeves don’t have enough juice for a rebuild. That all has a bad influence on the reliability and limit the engine life. It is hard to believe what the most engines will review 150,000-200,000 miles line.
Toyota A25A-FKS 2.5 D-4S Engine Specs
|Manufacturer||Toyota Motor Corporation|
|Cylinder block material||Aluminum|
|Cylinder head material||Aluminum|
|Fuel system||Direct/Multipoint Fuel Injection|
|Number of cylinders||4|
|Valves per cylinder||4|
|Bore, mm||87.5 mm (3.43 in)|
|Stroke, mm||103.4 mm (4.07 in)|
|Displacement, cc||2,487 cc (152 cu in)|
|Type of internal combustion engine||Four-stroke, naturally aspirated|
|Power, hp||177-205 hp (283 kW)/5,700-6,600|
|Torque, lb ft||162-184 lb-ft (220-250 Nm)/3,600-4,800|
|Engine oil weight||SAE 0W-16|
|Engine oil capacity, liter||4.5 (4.8 qt)
0.3 (0.4 qt) – oil filter.
|Oil change interval, mile||10,000 (15,000 km) /12 month|
|Applications||Toyota Camry XV70, Toyota Avalon, Toyota RAV4|
Toyota A25A-FKS 2.5 D-4S Engine Modifications
The A25A-FXS. The special version for hybrid cars application. It has a greater compression ratio 14.0:1 and slightly less power output.